THE 9/11 MEMORIAL is located at the site of the former World Trade Center complex.
The 8-acre plaza features two enormous waterfalls and reflecting pools, each about an acre in size, set within the footprints of the original twin towers. The names of those who perished are engraved in the edges of the reflecting pools. The pavilion is in between is the entrance to the museum below the plaza.
With its grove of 415 swamp white oak trees, the Memorial's plaza is an actual green roof for the structure housing the 9/11 Memorial Museum, a train station and other facilities 70 feet below street level.
One of the most striking aspects of the pavilion is its glass and steel atrium along the northwest corner, with two iconic "tridents" salvaged from base of the twin towers.

The 9/11 Memorial opened on 9/11/2011, but requires visitor passes which have been booked for several weeks.
The Tribute WTC Visitors Center at 120 Liberty St (near Greenwich) is open.
The site itself is still surrounded by a construction fence, but you can get into the Museum with a reservation.
It is projected to be completed in the second quarter of 2012.
In addition to the 8-acre plaza the new WTC site includes another 8 acres surrounding the plaza with office buildings, retail space, and a
transportation hub. One of these buildings (7 WTC) has already been completed and two
are under construction. 1 WTC - Freedom Tower, the building directly north of the North Pool, will have over
100 stories and stand taller at 1,776 feet (America's tallest building) than the original Twin Towers. It is scheduled for completion sometime in 2013.

911 Memorial Museum Pavilion from the World Financial Center with reflection of the flag from 1WTC on the atrium.

Picture taken thru a hole in the construction fence on Greenwich St. 9/13/2011

Design:
Following the destruction of the World Trade Center on September 11, 2001, there was much debate regarding the future of the World Trade Center site. Proposals began almost immediately, and by 2003, the Lower Manhattan Development Corporation organized a competition to determine how to use the land. Public rejection of the first round of designs, the "Preliminary Design Concepts", led to a second, more open competition in December 2002, the "Innovative Design Study", in which a design by Daniel Libeskind was selected. This design went through many revisions,[16] largely because of disagreements with developer Larry Silverstein, who held the lease to the World Trade Center site on September 11, 2001